noun, plural bound·a·ries.
Also called frontier. Mathematics. the collection of all points of a given set having the property that every neighborhood of each point contains points in the set and in the complement of the set.
Origin of boundary
1. Boundary, border, frontier share the sense of that which divides one entity or political unit from another. Boundary, in reference to a country, city, state, territory, or the like, most often designates a line on a map: boundaries are shown in red. Occasionally, it also refers to a physical feature that marks the agreed-upon line separating two political units: The Niagara River forms part of the boundary between the United States and Canada. Border is more often used than boundary in direct reference to a political dividing line; it may also refer to the region (of, for instance, a country) adjoining the actual line of demarcation: crossing the Mexican border; border towns along the Rio Grande. Frontier may refer to a political dividing line: crossed the Spanish frontier on Tuesday. It may also denote or describe the portion of a country adjoining its border with another country ( towns in the Polish frontier ) or, especially in North America, the most remote settled or occupied parts of a country: the frontier towns of the Great Plains. Frontier, especially in the plural, also refers to the most advanced or newest activities in an area of knowledge or practice: the frontiers of nuclear medicine.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
noun plural -ries
something that indicates the farthest limit, as of an area; border
- the marked limit of the playing area
- a stroke that hits the ball beyond this limit
- the four runs scored with such a stroke, or the six runs if the ball crosses the boundary without touching the ground
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Online Etymology Dictionary, © 2010 Douglas Harper